An adaptive equalizer is known in the mobile communication as a technology which can be used to eliminate interferences. The adaptive equalizer has long been used to combine and/or eliminate inter-symbol interferences as occurring between direct signals and delayed signals which have different delay times each other from a common origin. A conventional example of a technique of detecting a symbol sync timing for a received signal which is used in an adaptive equalizer will be described below. According to the conventional technique, the symbol timing has been synchronized with the 1st path representing a path having the eariest arrival. An arrangement for this instance is shown in FIG. 1. While not shown, a transmitter initially transmits a long-termed sync word sequence whose pattern is already known to the receiving side, followed by the transmission of data representing information content to be transmitted. On the receiver side, a received signal from the transmitter is amplified and demodulated into a baseband signal, which is then converted into a digital sequence. The received signal in the form of the digital sequence is input to an input terminal 11, and a channel response is estimated by using a correlation between the received signal and a sync word signal from a sync word generator 12 in a correlator 13. The channel response or the output signal from the correlator 13 changes, for example, in a manner illustrated in FIG. 2. The correlation output signal Sigc is compared with threshold signal Ths from a threshold signal presetter 14 in a symbol sync timing generator 15. A first timing t1 when the correlation output signal Sigc exceeds the threshold signal Ths is detected, thus obtaining a symbol sync timing for the 1st arrival path. A sampler 16 samples a digitized received signal from the input terminal 11 with the symbol sync timing signal, and a sampled output signal is fed to an adaptive equalizer 17, which applies an adaptive equalization to the sampled signal to deliver a decided symbol sequence to an output terminal 18.
In the conventional technique in which the symbol sync timing is set to the timing of 1st arriving path, there is a problem that if an equalization rage is limited in the time domain, there may occur a correlation output signal having a substantial power located outside the equalization range, resulting in a failure to achieve significant performances and thus a degradation in the response.